The neurotoxins of Clostridium (BoNT) are the most toxic proteins to humans and are Category A reagents. BoNTs (approximately 150,000 kDa) are zinc-dependent proteases that comprise a group of seven proteins designated as serotypes A through G. BoNT(A-G) share similar AB structure-function properties, but possess limited primary amino acid homology. BoNTs elicit flaccid paralysis through the cleavage of SNARE proteins that are part of the docking components of fusion vesicles. The B component of BoNT binds to receptors located on neuronal cells, yielding the trophism of this intoxication. While the paralysis elicited by each A-G serotype of BoNT is clinically similar, each serotype of BoNT cleaves individual SNARE proteins at specific amino acids. NIAID has identified the development of therapeutics and vaccines against BoNT as high priority bio-defense products. This research proposal is an inter-institutional effort to develop vaccine and therapeutic interventions against inhalation botulism. The focus on BoNT link the expertise of Eric Johnson, Sc.D., who has 17 years of research experience on the genetics and molecular biology of BoNT with researches whose expertise span the fields of immunology, bacterial pathogenesis, and combinatorial chemistry. The specific aims of the proposal are to (i) engineer a recombinant holo-BoNT toxoid for vaccine and basic research on intoxication; (ii)identify epitopes within BoNT that can be targeted to neutralize toxin action and small molecular-weight inhibitors of BoNT catalysis, which can be used for therapeutic intervention; and (iii) identify the BoNT receptor on neuronal cells to subsequently generate soluble receptor peptides for intoxication intervention. Completion of the goals of this proposal will address the immediate needs of our populous with respect to vaccine and therapeutic interventions against inhalation botulism and identify new avenues of research to address the pathology associated with this intoxication.